The present invention relates to novel 1,8-naphthyridin-2-one derivatives having an anti-inflammatory activity and which are useful for the treatment of rheumarthritis.
Rheumarthritis, which is characterized by inflammation and pain of articulations, shows a morbidity rate of 3-4%. While pathogenesis of rheumarthritis is not fully clarified, steroid type and non-steroid type anti-inflammatory agents have been used for therapy of rheumarthritis. In contrast to other non-steroid type anti-inflammatory agents, piroxicam (U.S. Pat. No. 3,591,584) and RU-43526 [J. Med. Chem., 31, 1453 (1988)] have no carboxylic acid moiety. ##STR3##
As to 4-hydroxy-1,8-naphthyridin-2-one derivatives, the following compounds represented by formula (A) are disclosed. ##STR4##
(1) A compound of formula (A) wherein R.sup.A is phenyl and R.sup.B is nitro having anti-allergic activity (Japanese Published Unexamined Patent Application No. 36694/77).
(2) A compound of formula (A) wherein R.sup.A is phenyl and R.sup.B is butyl having anti-ulcer activity (Sch 12223) [J Pharm. Exp. Ther., 246, 578 (1988)].
(3) Compounds of formula (A) wherein R.sup.A is alkyl, aralkyl, or the like and R.sup.B is carbamoyl, N-alkylcarbamoyl, N-alkoxycarbamoyl, or the like having anti-ulcer activity (U S. Pat. No. 4,215,123).
(4) Compounds of formula (A) wherein R.sup.A is alkyl or the like and R.sup.B is ethoxycarbonyl [J. Med. Chem., 30, 2270, (1987)].